1. Field
This invention relates to an electrostatic transfer reproduction apparatus and, more particularly, to an improved control device thereof for effecting rapid operation thereof.
2. Description of the Prior Art
In well-known continuous electrostatic printing processes, a photoconductive surface is continuously moved in a closed loop past various processing stations. Often, such systems include an imaging station which incorporates a moving optical projection system which projects a light image of a master onto the moving plate thereby creating a latent electrostatic image thereon. The moving optical projection system scans the master in the direction of plate travel so that the plate "sees" a continuous image of the master as it moves past the imaging station. The latent image on the plate is thereafter developed at a developing station, and the image is transferred to a substrate at a transfer station. When making multiple copies of the same master with such prior devices, it has been necessry for the system to wait for the optical system to return to its initial position prior to automatically initiating the second reproduction cycle. As devices have been constructed with ever increasing processing speeds, the delay time has accounted for a substantial portion of each reproduction cycle.
Prior attempts to avoid the delay introduced by the resettng optical projection system have suggested redeveloping the electrostatic image without reimaging the master. While such systems operate continuously without a delay thereby occasioning a marked increased in throughput, the quality of the reproduced copies rapidly degrades as the number of such redeveloped copies increase. That is, when a large number of copies are required, the first several copies produced by redeveloping the latent image without reimaging have virtually the same quality as the first copy produced by the system. However, each transfer operation and each redevelopment operation tends to degrade the electrostatic latent image on the plate thereby causing subsequent redeveloped copies to degrade in quality. Accordingly, the use of such a prior system would require operator intervention to reinitiate the system when image quality degraded below that which the operator thought was good image quality, thereby losing the time efficiencies of the redevelopment process. Accordingly no commercially successful system utilizing redevelopment has been introduced since such systems are only effective for producing a relatively small number of high quality copies of the same master.